Recent analyses have shown that many eukaryotic genes change position or mobility when induced. These changes occur independently in each cell in a population, but to date gene expression has been measured as an average across many thousands of individuals or as a frozen instant in time in a single fixed cell. These limitations have complicated analysis of the relationship between gene position, mobility, and transcription. To address this problem, we have developed a reporter assay that allows convenient and simultaneous monitoring of both the position and expression of a given gene in a single living cell. As a result, we have discovered that deletion of MIG1, the extensively-studied repressor of approximately 300 glucose-regulated genes in the model eukaryote Saccharomyces cerevisiae, has a profoundly asymmetric effect on expression from the promoter of its archetypical target SUC2;repression is lost in only half of all cells, and transcription remains fully inhibited in the other half. The goal of Specific Aim 1 is to determine whether these two populations are truly distinct, or if individual cells can switch between populations. If switches occur, we will determine what relationship, if any, exists between gene position and changes in expression state. The goal of Specific Aim 2 is to identify the molecular mechanism or mechanisms that mediate repression of SUC2 in the absence of MIG1. Understanding glucose-regulated gene expression is key to the development of effective therapies for diabetes, metabolic syndrome, and cancer;the conserved AMP kinase pathway, which operates upstream of Mig1, has been implicated in all of these diseases. The studies described here will apply genetic, cell biological, biochemical, and genomic techniques, thereby making full use of the integrative approach to problem solving that is available in the S. cerevisiae model system. The ease with which this organism can be grown and manipulated also makes it an ideal choice in providing research opportunities for undergraduate students. PUBLIC HEALTH RELEVANCE: Understanding glucose-regulated gene expression is key to the development of effective therapies for diabetes, metabolic syndrome, and cancer. The AMP kinase (AMPK) pathway, which responds to the presence of glucose in eukaryotic organisms from yeast to humans, controls the function of numerous transcription factors. The long-term objective of this project is to understand how nuclear organization contributes to the regulation of genes targeted by the AMPK pathway.